The present invention relates to a technique for backing up data stored on storage servers in a computer system comprising individual storage servers for each client connected over the Internet.
Storage servers which store data used by servers and clients are important for periodically backing up data in order to prevent accidental loss of data. Data can be backed up, for example, to certain recording media by sending the data to a media server connected by a fiber network to the storage servers (see, for example, U.S. Pat. No. 6,460,113). Examples of backup recording media which can be used include portable recording media such as tape media, optical disks, and opticomagnetic disks, as well as stationary recording media such as magnetic disks and semiconductor memory devices.
Recently there has been continuing development of services which involve exclusive maintenance and management of storage servers, web servers, and the like, and which give clients access to the functions of such devices over the Internet. Ordinarily, such servers are located in facilities referred to as data centers managed by service providers. Storage servers located in data centers are sometimes individually prepared for each client to limit access by other clients.
An example of a method for backing up data stored in storage servers in such a data center is to individually prepare media servers for each client in the same manner as storage servers. In this method, however, the increase in facility resources and the greater complexity of the facilities can result in the risk of less maintenance. One possible solution is to connect one media server over a network to a plurality of storage servers. However, in that method, the storage servers for which pains have been taken to individually provide each client end up being connected to each other over the network, with the danger of client data leaking over the network during data backup to other clients.